Navigation

The suspension setting process provided here is a “Basic” methodical guide to providing a way to update you current suspension to the style of riding to best suit your needs. When suspension works correctly the bike will be much more enjoyable to ride.

One of the major keys to a
successful suspension setup is the condition of the components.
Before attempting any setting changes, check to make sure your
bike’s fork and shock are in good working order. This includes
replacing leaky seals, lubricating sticky linkage bushings, and
changing old fork or shock oil. If your current components have
more than 15,000 hard miles on them, you can bet it’s time for a
rebuild. Check your steering head bearings for notchiness or
tightness and replace them if needed. And most importantly,
squared-off or worn out tires will mask almost any suspension
change you make.

The following is an outline of
the major steps that will be taken to bring you bike into a good
riding setup that will help you enjoy your riding
experience.

bikesetup.xls is an Microsoft Excel spreadsheet template which provides a way for you to follow the progressive iterations of you suspension modifications.

Steps of the Game

The following sections of this
article go into the dynamics of what happens when changes are made
to the suspension. I state that the adjustment process is a game
because of the tradeoffs that must be made. There are tradeoffs
that can be given for each adjustment that you make to your bike.
These tradeoff must be balanced against the gains that a specific
adjustment makes to improve your suspension.

TYPES OF RIDING

The types of riding determine
you expected setup. As a street rider typically expects a more
compliant and plush suspension that needed to soak up the rougher
roads and to be more comfortable while riding. This more relaxed
stable setup will actually help over the long haul of street riding
because of less rider fatigue with a stable. Track riding has
different goals of pushing the bike so it provides the optimum
effectives for the track. The track does not translate directly
into a good street bike and vice versa.

Determining the style of the
rider also affects the way your setup reacts for a particular
person. A smooth rider will have a different setup compared to a
point and shoot style of riding. It is all relative to you and your
bike.

It’s important to take good
notes–and lots of them, especially for the track. Along with your
initial settings, you should also write down some baseline figures
for things such as fork oil weight and amount, ride height, spring
rates, and so on. Record any changes you make so that you can refer
to them later. Also, keep notes for different types of riding
street, touring, tracks–as your setup will change depending where
you are and the conditions. Once you find that “magic” setup, don’t
be afraid to deviate from it and experiment; you may be able to
improve on what you have, and you can always go back to what you
wrote down in your notes.

STREET SETUP

The first step to a good setup is setting static sag. For street purposes,
front sag should generally be between 30 and 35mm, and rear sag
between 25 and 30mm. Don’t vary from these numbers if you’re
heavier or lighter–that’s the whole idea of measuring sag while you
are on the bike. An easy way to check if your shock spring rate is
in the ballpark is to measure the rear “free” sag, that is, the sag
without your weight on the bike. This number should be between 0
and 5mm–with the bike off its stand and on its own, you should be
able to lift the rear end just slightly and top out the suspension.
If your bike is topped out at rest, you need a stiffer spring,
because you have got a lot of preload dialed in to achieve the
correct static sag. Alternately, if your bike has a lot of free sag
(you can lift the rear a bunch before it tops out), you need a
softer spring.

Compression damping can be initially set as
follows: It is difficult to set compression damping
without riding your motorcycle and feeling how its suspension
works. What feels nice and plush at a standstill may turn out to be
too harsh at speed, and compression damping is sometimes set by
personal preference as opposed to a definite optimum. Start with
the compression adjusters in the middle of their adjustment range,
and take your bike for a spin. Working with the front and rear
individually, soften the damping adjuster, and try your bike again
over the same road. Is your handling better? Worse? The same? Try
again, this time with the damping stiffer than what you started
with. Continue experimenting, making adjustments accordingly. As
with rebound damping, it’s always best to err on the light side
with compression, and for the same reasons.

Rebound damping can be
initially set as follows: With the sag properly set and
the bike at rest and off its stand, firmly push on the triple clamp
(don’t hold on the brake or push the handlebar) or seat. When you
let go, the suspension should rebound quickly to its original
position–but not beyond. If it takes more than approximately one
second for the suspension to return to position, less rebound
damping is needed. If the fork or shock over-extends past its free
sag, and then compresses again, more rebound damping is required.
Street riding entails many different pavement characteristics, and
the road is generally bumpy compared to a racetrack, so it’s better
to err on the soft side if you are unsure. This will also give you
the added benefit of a smooth ride for daily use; you can always
dial in a tad more rebound when you get to your favorite road where
the surface is more of a known quantity.

One final check–with your bike
off its stands, place your hands near the rear of the tank, and
push down. A well-balanced setup will have both ends of your bike
compressing and returning at approximately the same rate with this
push. If the front compresses or rebounds different than the rear,
attempt to match them, keeping within the parameters established
individually.

TRACK SETUP

As with the street setup,
first ensure that your bike’s suspension components are in good
working order, and you have relatively new tires installed. One
word of caution regarding setup and tires: Don’t get dragged into
adjusting your suspension to account for tire wear over the course
of a track day without taking notes. You’ll be amazed at how poorly
your bike handles when you put new tires back on and keep the
shagged-tire suspension settings.

In general, a bike set for
track use is stiffer than a streetbike, due to the increased
acceleration, braking and cornering forces involved. Static sag for
track bikes should be in the range of 25 to 30mm–somewhat tighter
on the fork than a street setup. Similarly, compression and rebound
damping should be somewhat stiffer. Avoid tightening your rebound
arbitrarily; you still want the suspension to rebound within one
second to its static position after pressing on the bike, but not
overshoot.

Ride Height can be initially set as follows: If you have a ride height
adjuster on your aftermarket shock, set it to the same length as
the stock unit for a start. Similarly, begin with your fork at the
stock height in the triple clamps. Use the handling scenarios and
the chart to determine if you need to change your bike’s attitude.
Generally, for a track bike with a steering damper, you’ll want to
quicken the steering as much as possible by lowering the front end
or raising the rear, while still retaining stability and without
sacrificing rear end traction.

Prior to making suspension changes

There are a few adjustment to
your bike setup that should be done prior to making adjustments to
your suspension. These adjustments could affect handling to a
certain degree, and throw off getting the proper feedback. As
stated earlier in this article it is important to have your bike in
proper running order.

Fill out the check sheet
Check chain alignment. If not correct, sprocket wear is
increased.
Proper tire balance and pressure. If out of balance, there will be
vibration in either wheel
Steering head bearings and torque specifications, If too loose,
head will shake at high speeds.
Front end alignment. Check wheel alignment with triple clamps. If
out of alignment, fork geometry will be incorrect and steering will
suffer.

Chain Adjustment:

Proper chain adjustment
minimally affects the overall length of the rear swingarm. Although
this is not significant it is a factor because of other the proper
chain tension can have an impact on how the suspension reacts. This
negative effect has become less pronounced with new motorcycle
models because of the suspension pivot being located so close to
the counter shaft.

MAX EXTENSION You should check
the chain tension with the bike on its wheels and preferably with
someone sitting on it. You want the chain at maximum extension – or
with the front sprocket, swingarm and rear sprocket all in line
with each other.

It probably won’t be lined up
perfectly, but plonking yourself in the saddle and using your own
weight (or that of a friend) is a good start. Wiggle the lower run
of the chain as close as possible to the middle. You should have
about 15-20mm of slack up and down.

WHY BOTHER? Good question. A
tight chain will place a lot of unnecessary strain on itself, the
sprockets and even gearbox bearings. Keep running chains too tight
and you can do a lot of expensive damage. Have it too loose and you
risk the chain thrashing around and causing increased sprocket wear
or, in a worst case, throwing itself off the sprockets altogether
and causing a crash.

A well adjusted and lubricated
chain transmits the power smoothly (you can actually see the
difference on a dyno), lengthens the service life, smoothes out
your gear changes and makes the bike feel better to
ride.

Wheel Alignment:

If you have a
conventional chain-drive bike, you’ll see the back wheel’s position
can be altered with the adjusters. Whenever you tension the chain
or move the wheel for any reason, you generally just line it up
against the alignment marks stamped on the swingarm. If the axle is
back three-and-half notches on one side, you make sure it’s back
three-and-a-half on the other. Simple.

The trick is
to get a ball of twine, or you can do this exercise if you can
somehow find two straight edges that are longer than the bike. The
latter is a big call, so we’ll stick with the string method – yep,
this is ye olde “stringlining”, of which you may have heard your
mates speak.

Usually this
is easiest with the bike on the sidestand (the center stand usually
gets in the way) and propped up as close as possible to vertical. A
race stand is often a good option.

Wrap the
string around the front of the front wheel, as high as possible
without snagging fairings and associated under-bike hardware when
you run each end of the twine under the machine. The pics will give
you the idea.

From there
the plan is to get the front wheel straight, and then the rear
wheel adjusted so it is too. What you want to end up with is what
we’ve shown in the main diagram – where the distances “A” (the gap
between the string and the edge of the tire) and “B” (ditto) on the
trailing edge of the front wheel are equal to each other; And the
distances “A” and “B” on the trailing edge of the back wheel are
equal to each other. (Note: the A/B up front does not have to match
A/B on the back.)

This is often
best done with two people, one working on each end of the bike. It
is a great help to have oil cans/bricks/jackstands to hold the
loose ends of the string for you while you fiddle.

Getting it
all lined up will be a bit of a fiddle, but simple enough assuming
the bike is straight. The exact method isn’t critical, so long as
you end up with a result that looks like our diagram.

If you cannot
get them to align, it is likely the frame isn’t straight, or the
bike might even have been designed with the rear wheel offset from
the front.

Tire Pressure:

You’ll get a lot of opinions
on what tire pressure to run, but the correct tire pressure for you
is not a matter of polling other rider’s opinion. Here are the
basics you’ll need to decide for yourself. “Dennis Smith of
Dunlop’s Sport Tire Services recommends an increase of two to four
pounds in front tires and six to eight in the rear
(sportsrider.com)”. While the most scientific means of determining
if a particular pressure is the use of a pyrometer to assess
whether the rubber has reached the manufacturer’s recommended
temperature, charting the pressure increase of a tire after track
sessions will give a good impression of how hard a tire is
working.

Stamped on the outside of many
of your tires is a recommended tire pressure range. (At least an
upper limit.) For longest tire life it is my recommendation that
you strive to keep them at the higher limit of those
recommendations (regardless of what your motorcycle owner’s manual
might say to the contrary.) Further, this pressure should be
determined while the tires are cold – meaning, have not been used
for a couple of hours.

Start with the bike
manufacturer’s recommendation in the owners manual or under-seat
sticker. This is the number they consider to be the best balance
between handling, grip and tire wear. Further, if you’re running
alloy wheels on poor pavement, consider adding 2 psi to the
recommended tire pressure just to reduce the likelihood of pothole
damage. Just as you would for a car, increase the pressure 2 psi or
so for sustained high speed operation (or 2-up riding) to reduce
rolling friction, increase tire life, and casing
flexing.

In order to get optimum
handling a tire has to get to its optimum temperature, which is
different for each brand of tire and different uses. Most of us
don’t have the equipment needed to measure tire temperature
directly so we measure it indirectly by checking tire pressure
since tire pressure increases with tire temperature. Tire
temperature is important to know because too much flexing of the
casing of an under-inflated tire for a given riding style and road
will result in overheating resulting in less than optimum grip.
Over-pressurizing a tire will reduce casing flexing and prevent the
tire from getting up to the optimum operating temperature and
performance again suffers.

Street

A technique for those wanting
to get the most out of their tires on the STREET is to use the
10/20% rule.

First check the tire pressure
when the tire is cold. Then take a 30-40 minute ride on your
favorite twisty piece of road to get your tire temperature up, then
measure the tire pressure immediately after stopping.

If the pressure has risen less
than 10% on the front or less than 20% on the rear, the rider
should remove air from the tire (to increase heating affect of
carcass flex). So for example, starting at a front tire pressure of
32.5 psi should bring you up to 36 psi hot. Once you obtain this
pressure increase for a given rider, bike, tire, road and road
temperature combination, check the tire pressure again while cold
and record it for future reference.

Each manufacturer is
different. Each tire model is different.

A tire design that runs
cooler needs to run a lower pressure (2-3 psi front) to get up to
optimum temperature. Remember carcass flex to generate additional
heat.

The rear tire runs hotter
than the front tire on both road and track. So the rear tire
cold-to-hot increase is greater.

Dropping air pressure has the
additional side effect of scrubbing more rubber area, and can
additionally add more traction at the cost of a little
stability

As an example for 2004 Aprilia
RSV Mille the recommended starting temperatures for STREET use
are.

Rear Tire 39.4 deg Cold which
in turn should be approximately 45-47 deg Hot (7-9psi
increase)

Please note that
these numbers tend to be too high for maximum traction but in turn
increase the life of the tire.

Track

Track tire pressure is a
different animal altogether. With track requirements the tire
pressure is a +/- game which has a goal to getting
to the proper temperature and pressure to maximize grip, feel, and
stability.

For the track you’ll have to
drop the cold tire pressures an additional 10/20%. Track operation
will get tires hotter (increasing the cold-to-hot pressure range)
so starting at say 32/30 psi now should bring you up to the proper
opreating temperature AND create enough tire pressure to maximize
contact patch AND create enought feel and stability for the track.
With these goals in mind the tire should be approximatly 35/36 psi
when fully heated (at optimum tire temperature).

Since track riding put
tremendous stresses on a “STREET” tire the tire heats up more than
if it was on the street. “Race” tires will have different heat
capabilities and are able to withstand the higher forces of a track
better (ie cooler) than a street tire. The lower the tire pressure
the more the tire deforms. The more the tire deforms, the more
friction there is between the tire and the road surface. The more
friction, the more heat. The more heat, the greater the opportunity
the tire has to regenerate itself by shedding the ‘used’ layers of
rubber (to a point). This deformation of the tire also creates a
bigger contact patch at the cost of a little stability (ex rear
wiggle).

Different riders have
differerent starting pressures. You have two riders, ‘super fast
john’, and ‘average joe’ go out on the recommended 31psi pressure
and ‘averages joe’s’ tires come in with the correct hot pressure
(lets say 34-35 psi for example using Pirelli’s reccommended hot
pressure) you can bet that because that ‘superfast John’ will be
working the tire harder, spinning it more and his tire might come
in reading 37psi.

This would mean that to reach the target pressure of 34 psi
which is the pressure and also temp that the tire works the best,
‘superfast john’ will need to take 3psi out of his tires and be
starting at 28psi cold.

Tire Heat Cycles

Another good idea is to track
is the number heat cycles your tires experience. Each time your
TRACK tires get hot they release chemicals from deep within the
rubber. As the chemicals are released the tires lose some of their
grip. You can see tires that are hardly worn lose their grip due to
heat cycles. Count the number of heat cycles that your tires go
through and you may find a repeatable pattern that lets you know
when to get that new set. Street tires a specifically designed to
have many heat cycles whereas Race tires will have a fewer
available heat cycles before the tire gets hard. A good indication
of the tires having too many heat cycles on them is that they look
fine as far as the tires not being overly worn, but the are a
blue/purple color on the edge of the tire. This doesnt mean that
you cant use them any more but more you just have to be ready for
them to have a little less grip than they used to.

Q: What is a heat cycle on
racing tires? How does it affect the wear and grip of a
tire?

A: A “RACE” tire heat cycle is
when a tire is brought up to operating temperature and run for some
laps, then allowed to cool. Taking a tire through a heat cycle
changes its chemistry. In most instances it stabilizes the tire
compound by decreasing its heat generation. But that process also
slightly increases the durometer hardness of the tire. So scrubbing
the tires (one heat cycle run) will help the tires run a little
cooler and wear slightly better. Successive heat cycles will
continue this curing process. Eventually the tires will not provide
nearly enough grip because they have gotten too hard, but they will
wear like iron. Each heat cycle cures the tire rubber more and
makes in harder. Keep good records on each of your tires so you
know how much use – and how many heat cycles – each of your tires
has.

Heat Cycles: Heating your
tires for practice and then keeping the warmers on between practice
sessions saves Heat Cycles (the # of times a tire gets hot and then
cools) which age your tires (the tire goes “off” meaning the best
grip is gone). If the
correct operating temp for your tire is 180′ F (just a number i
pulled out of the air), and with a brand new tire it takes 2 laps
to warm you tires up to operating temperature, then the next day (
i am spacing it out longer than a session) it may take 3 laps, then
4 laps etc. at a certain temperature a tire’s compounds have a
chemical reaction which makes the tire sticky and gives it more
grip, after each heat cycle the tire hardens and then it takes
longer to get to that temperature. Each heat cycle hardens the tire
(as explained before), if you cool the tire very slowly it is less
likely to harden as much as if you pulled off the track, parked the
bike on a stand and let the ambient temp cool the tires. this is
why a lot of trackday riders/racers will put their tire warmers on
but not plug them in, the insulated blanket will slow down the
cooling effect. chickenhawk tire warmers also have a low temp
setting where you can almost have the warmers on the low setting
all day.

Tire Care

When you are accounting for
your riding style and the way different days, streets, tracks can
be accounted for. All bikes will have different characteristics
which means my starting riding temperature is different than
yours.

Additionally with the colder
months of the year tire pressures and the effect of temperature can
greatly affect the overall pressure.

Time and outside temperature
effect the pressure within your tires. It is NORMAL for a tire to
lose about 1 pound per square inch (psi) per month. Outside
temperatures affect your tire pressure far more profoundly,
however. A tire’s pressure can change by 1 psi for every 10 degrees
Fahrenheit of temperature change. As temperature goes, so goes
pressure.

For example, if a tire is
found to have 38 psi on an 80-degree mid-summer day, it could lose
enough air to have an inflation pressure of 26 psi on a 20-degree
day six months later. This represents a loss of 6 psi over six
months and an additional loss of 6 psi due to the 60 degree
temperature reduction.

At 26 psi, your tire is
severely under inflated and dangerous!

What is being illustrated here
is that you MUST check your tire pressure on a regular basis (about
once a week is reasonable) and to be particularly aware of it on
cold days.

As an additional note of
caution: New tires tend to be very slippery when ridden for the
first time. It is recommended that an easy scrubbing in over 20-50
miles of riding. This will allow the tire to get rid of the mold
catylist used for removing the tire and provide an initial heating
which releases a layer of rubber to provide optimum
traction.

Suspension stroke

A sportbike should normally
not use its full suspension stroke, although on some circuit one or
two big bumps or hollows can cause the suspension to bottom. Also
landing of front wheel after wheelies can cause excessive use of
the front fork stroke. If suspension bottoms in big bump or hollow,
it should not automatically mean that the suspension should be set
more hard. However, if suspension bottoms at the place were the
maximum grip is essential the tire cannot create the best traction,
because it also has to perform as spring. Adjusting the setting is
necessary. During every riding session the suspension stroke should
be carefully checked. When tire grip and lap times improve, the
suspension has a harder job. So, setting must be set harder. On the
opposite, when it starts raining tire grip and lap times go down,
in that case a softer setting should be applied.

Lets Get Busy with how to adjust Suspension Setup

Types of Adjustment

On most forks,

Rebound Damping (1) – the screw adjustment at the top is rebound
damping (not to be confused with the larger spring preload
adjuster)

Preload adjuster (3)- Is the larger nut on the top of the front
forks (not to be confused with the smaller rebound damping).
Movement of the Forks within the Triple Clamps, can be substituted
for the preload adjuster.

Compression Damping (2) – the one on the bottom near the axle is
compression damping.

Rear Shock

Preload adjuster (3&4) – Is adjusted by using a C-Spanner or the
appropriate wrench/spanner.

Compression Damping (2) – is the adjuster on the reservoir usually a knob or a
screw.

Contrary to the fork’s
controls, rear rebound damping is changed from the bottom of the
shock.
Change the shock’s compression damping on the reservoir
The fork rebound adjuster, like all the damping controls, screws in
for firmer and out for softer.
The compression damping adjuster usually resides on the lower
portion of the fork.

Setting Static Sag

No matter what
shock or fork you have, they all require proper adjustment to work
to their maximum potential. Suspension tuning isn’t rocket science,
and if you follow step-by-step procedures you can make remarkable
improvements in your bike’s handling characteristics.

The first step to
setting up any bike is to set the spring sag and determine if you
have the correct-rate springs. Spring sag is the amount the springs
compress between fully topped out and fully loaded with the rider
on board in riding position. It is also referred to as static ride
height or static sag.

If you’ve ever
measured sag before, you may have noticed that if you check it
three or four times, you can get three or four times, you can get
three or four different numbers without changed anything. We’ll
tell you why this occurs and how to handle it.

REAR END SAG

Step 1: Extend the suspension completely and
measure. By getting the wheel off the ground. It helps to
have a few friends around. On bikes with sidestands the bike can
usually be carefully rocked up on the stand to unload the
suspension. Most race stands will not work because the suspension
will still be loaded by resting on the swingarm rather than the
wheel. Measure the distance from the axle vertically to some point
on the chassis (metric figures are easiest and more precise; Mark
this reference point because you’ll need to refer to it again. This
measurement is L1. If the measurement is not exactly vertical the
sag numbers will be inaccurate (too low).

What you are going to do is
get the average of the compression with a rider on the bike from
two different directions

Step 2: Downward
Compression suspension with Rider on the bike and measure.
Take the bike off the stand and put the rider on board in riding
position. Have a third person balance the bike from the front. If
accuracy is important to you, you must take friction of the linkage
into account. This is where our procedure is different: We take two
additional measurements. First, push down on the rear end about
25mm (1″) and let it extend very slowly.

Where it stops, measure the
distance between the axle and the mark on chassis again. If there
were no drag in the linkage the bike would come up a little
further. It’s important that you do not bounce!
This measurement is L2.

Step 3: Upward
Compression of suspension with Rider on the bike and
measure. Have your assistant lift up on the rear of the
bike about 25mm and let it down very slowly. Where it stops,
measure it. If there were no drag it would drop a little further.
Remember, don’t bounce! This measurement it L3.

Step 4: Do the number
crunch: The spring sag is in the middle of these two
measurements. In fact, if there were no drag in the linkage, L2 and
L3 would be the same. To get the actual sag figure you find the
midpoint by averaging the two numbers and subtracting them from the
fully extended measurement L1: static spring sag = L1 -[(L2 + L3) /
2].

Step 5: Adjust the
preload with whatever method applies to your bike. Spring
collars are common, and some benefit from the use of special tools.
In a pinch you can use a blunt chisel to unlock the collars and
turn the main adjusting collar. If you have too much sag you need
more preload; if you have too little sag you need less preload. For
road race bikes, rear sag is typically 25 to 30mm. Street riders
usually use 30 to 35mm. Bikes set up for the track are compromise
when ridden on the street. The firmer settings commonly used on the
tract are generally not recommended (or desirable) for road
work.

You might notice the Sag
Master measuring tool (available from Race Tech) in the pictures.
It’s a special tool made to assist you in measuring sag by allowing
you to read sag directly without subtracting. It can also be used
as a standard tape measure.

Measuring front-end sag is
very similar to the rear. However, it’ much more critical to take
seal drag into account on the front end because it is more
pronounced.

FRONT END SAG

Step 1: Extend the suspension completely and
measure. Extend the fork completely by getting the bike
off the ground and measure from the wiper (the dust seal atop the
slider) to the bottom of the triple clamp (or lower fork casting on
inverted forks; Figure 2). This measurement is L1.

Step 2: Downward
Compression suspension with Rider on the bike and measure.
Take the bike off the sidestand, and put the rider on board in
riding position. Get and assistant to balance the bike from the
rear, then push down on the front end and let it extend very
slowly.

Where it stops, measure the
distance between the wiper and the bottom of the triple clamp
again. Do not bounce. This measurement is L2.

Step 3: Upward
Compression of suspension with Rider on the bike and
measure. Lift up on the front end and let it drop very
slowly. Where it stops, measure again. Don’t bounce. This
measurement is L3. Once again, L2 and L3 are different due to
stiction or drag in the seals and bushings, which is particularly
high for telescopic front ends.

Step 4: Do the number
crunch: Just as with the front, halfway between L2 and L3
is where the sag would be with no drag or stiction. Therefore L2
and L3 must be averaged and subtracted from L1 to calculate true
spring sag: static spring sag = L1 – [l2 + l3) / 2].

Step 5: Adjust the
preload. To adjust sag use the preload adjusters, if
available, or vary the length of the preload spaces inside the
fork.

Street bikes run between 25
and 33 percent of their total travel, which equates to 30 to 35mm.
Roadrace bikes usually run between 25 and 30mm.

This method of checking sag
and taking stiction into account also allows you to check the drag
of the linkage and seals. It follows that the greater the
difference between the measurements (pushing down and pulling up),
the worse the stiction. A good linkage (rear sag) has less than 3mm
(0.12″) difference, and a bad one has more than 10mm (0.39″). Good
forks have less than 15mm difference, and we’ve seen forks with
more than 50mm. (Gee, I wonder why they’re harsh?)

It is important to stress that
there is no magic number. If you like the feel of the bike with
less or more sag than these guidelines, great. Your personal sag
and front-to-rear sag bias will depend on chassis geometry, track
or road conditions, tire selection and rider weight and riding
preference.

Using different sag front and
rear will have huge effect on steering characteristics. More sag on
the front or less sag on the rear will make the bike turn more
slowly. Increasing sag will also decrease bottoming resistance,
though spring rate has a bigger effect than sag. Racers often use
less sag to keep the bike clearance, and since roadraces work
greater than we see on the street, they require a stiffer setup. Of
course, setting spring sag is only first step of dialing in your
suspension, so stay tuned for future articles on spring rates and
damping.

Typical setup for Sag

Bike
Type

Front
%

Front
mm

Rear
%

Rear
mm

Rear Free Sag
mm

Street Bikes

28-33%

30-35mm

28-33%

30-35mm

0-5mm

Road Race Bikes

23-27%

25-30mm

23-27%

25-30mm

0-5mm

Paul Thede – Race Tech
(909/594-7755)
Magazine: Sport Rider

SUSPENSION DAMPING SYMPTOMS

Here are some basic symptoms
of suspension damping problems that you might find affecting your
bike. Remember these are extreme examples; your symptoms may be
more subtle. You may also have to find an acceptable compromise on
either end of the adjustment spectrum. It all depends on how the
bike’s handling “feels” to you.

Front Fork

LACK OF REBOUND DAMPING (FORK)

The fork offers a supremely
plush ride, especially when riding straight up. When the pace picks
up, however, the feeling of control is lost. The fork feels mushy,
and traction “feel” is poor. After hitting bumps at speed, the
front tire tends to chatter or bounce. When flicking the bike into
a corner at speed, the front tire begins to chatter and lose
traction. This translates into an unstable feel at the clip-ons. As
speed increases and steering inputs become more aggressive, a lack
of control begins to appear. Chassis attitude and pitch become a
real problem, with the front end refusing to stabilize after the
bike is counter steered hard into a turn.

– Understeer!
– The front can feel unstable.

Symptoms:

Forks are plush, but
increasing speed causes loss of control and traction
The motorcycle wallows and tends to run wide exiting the turn
causing fading traction and loss of control.
When taking a corner a speed, you experience front-end chatter,
loss of traction and control.
Aggressive input at speed lessons control and chassis attitude
suffers.
Front end fails to recover after aggressive input over bumpy
surfaces.

Solution:

Insufficient rebound. Increase
rebound “gradually” until control and traction are optimized and
chatter is gone.

TOO MUCH REBOUND DAMPING (FORK)

The ride is quite harsh–just
the opposite of the plush feel of too little rebound. Rough
pavement makes the fork feel as if it’s locking up with stiction
and harshness. Under hard acceleration exiting bumpy corners, the
front end feels like it wants to “wiggle” or “tankslap.” The tire
feels as if it isn’t staying in contact with the pavement when on
the gas. The harsh, unforgiving ride makes the bike hard to control
when riding through dips and rolling bumps at speed. The
suspension’s reluctance to maintain tire traction through these
sections erodes rider confidence.

– Oversteering!
– It will give poor grip of the front tire.
– It feels like the front wheels will tuck under in
corners.

Symptoms:

Front-end dives severely,
sometimes bottoming out over heavy bumps or during aggressive
breaking.
Front feels soft or vague similar to lack of rebound.
When bottoming, a clunk is heard. This is due to reaching the
bottom of fork travel.

Solution:

Insufficient compression.
Increase “gradually” until control and traction are
optimized.

LACK OF COMPRESSION DAMPING (FORK)

Front end dive while on the
brakes becomes excessive. The rear end of the motorcycle wants to
“come around” when using the front brakes aggressively. The front
suspension “bottoms out” with a solid hit under heavy braking and
after hitting bumps. The front end has a mushy and semi-vague
feeling–similar to lack of rebound damping.

– Strong diving of the front.

Adjustment advice: Compression
damping should be adjusted together with front fork oil
level.

Symptoms:

Front-end dives severely,
sometimes bottoming out over heavy bumps or during aggressive
breaking.
Front feels soft or vague similar to lack of rebound.
When bottoming, a clunk is heard. This is due to reaching the
bottom of fork travel.

Solution:

Insufficient compression.
Increase “gradually” until control and traction are
optimized.

TOO MUCH COMPRESSION DAMPING (FORK)

The ride is overly harsh,
especially at the point when bumps and ripples are contacted by the
front wheel. Bumps and ripples are felt directly; the initial “hit”
is routed through the chassis instantly, with big bumps bouncing
the tire off the pavement. The bike’s ride height is effected
negatively–the front end winds up riding too high in the corners.
Brake dive is reduced drastically, though the chassis is upset
significantly by bumps encountered during braking.

– Good result during braking.
– Feels harsh over the bumps.

Symptom:

Front end rides high through
the corners, causing the bike to steer wide. It should maintain the
pre-determined sag, which will allow the steering geometry to
remain constant.

Front end chatters or shakes
entering turns. This is due to incorrect oil height and/or too much
low speed compression damping.

Solution:

First, verify that oil height
is correct. If correct, then decrease compression “gradually” until
chattering and shaking ceases.

Symptom:

Bumps and ripples are felt
directly in the triple clamps and through the chassis. This causes
the front wheel to bounce over bumps.

Solution:

Decrease compression “gradually” until control is regained.

Symptom:

Ride is generally hard, and gets even harder when braking or entering turns.

Solution:

Decrease compression “gradually” until control is regained.

REAR SHOCK

LACK OF REBOUND DAMPING (REAR SHOCK)

The ride is plush at cruising
speeds, but as the pace increases, the chassis begins to wallow and
weave through bumpy corners. This causes poor traction over bumps
under hard acceleration; the rear tire starts to chatter due to a
lack of wheel control. There is excessive chassis pitch through
large bumps and dips at speed and the rear end rebounds too
quickly, upsetting the chassis with a pogo-stick action.

The ride will feel soft or
vague and as speed increases, the rear end will want to wallow
and/or weave over bumpy surfaces and traction suffers.
Loss of traction will cause rear end to pogo or chatter due to
shock returning too fast on exiting a corner.

Solution:

Insufficient rebound: Increase
rebound until wallowing and weaving disappears and control and
traction are optimized.

TOO MUCH REBOUND DAMPING (REAR SHOCK)

This creates an uneven ride.
The rear suspension compliance is poor and the “feel” is vague.
Traction is poor over bumps during hard acceleration (due to lack
of suspension compliance). The bike wants to run wide in corners
since the rear end is “packing down”; this forces a nose-high
chassis attitude, which slows down steering. The rear end wants to
hop and skip when the throttle is chopped during aggressive corner
entries.

– The rear “jumps” on the bumps instead of following the
surface.
– The rear “jutters” under braking.
– It holds the rear down with the result that the bike will
understeer!
– It can cause overheating in the hydraulic system of the shock
absorber and make it fade, in other words, it will loose
damping when hot

Symptoms:

Ride is harsh, suspension
control is limited and traction is lost.
Rear end will pack in, forcing the bike wide in corners, due to
rear squat. It will slow steering because front end is riding
high.
When rear end packs in, tires generally will overheat and will skip
over bumps.
When chopping throttle, rear end will tend to skip or hop on
entries.

Solution:

Too much rebound. Decrease
rebound “gradually” until harsh ride is gone and traction is
regained. Decrease rebound to keep rear end from
packing.

LACK OF COMPRESSION DAMPING (REAR SHOCK)

There is too much rear end
“squat” under acceleration; the bike wants to steer wide exiting
corners (since the chassis is riding rear low/nose high). Hitting
bumps at speed causes the rear to bottom out, which upsets the
chassis. The chassis attitude is affected too much by large dips
and G-outs. Steering and control become difficult due to excessive
suspension movement

– The rear wheel start to bump sideways under acceleration out
of the corner.
– The bike will squad too much (rear is too low), that will cause
the front to loose grip..

Symptoms:

The bike will not turn in
entering a turn.
With bottoming, control and traction are lost.
With excessive rear end squat, when accelerating out of corners,
the bike will tend to steer wide.

Solution:

Insufficient compression.
Increase compression “gradually until traction and control is
optimized and/or excessive rear end squat is gone.

TOO MUCH COMPRESSION DAMPING (REAR SHOCK)

The ride is harsh, though not
quite as bad as too much rebound; the faster you go, the worse it
gets, however. Harshness hurts rear tire traction over bumps,
especially during deceleration. There’s little rear end “squat”
under acceleration. Medium to large bumps are felt directly through
the chassis; when hit at speed, the rear end kicks up.

– The rear wheel to slide
under acceleration .
– It can give a harsh ride over bumps.

Symptoms:

Ride is harsh, but not as bad
as too much rebound. As speed increases, so does harshness.
There is very little rear end squat. This will cause loss of
traction/sliding. Tire will overheat.
Rear end will want to kick when going over medium to large
bumps.

Solution:

Decrease compression until
harshness is gone. Decrease compression until sliding stops and
traction is regained.

Too soft spring ratio:
– Gives good traction in acceleration.
– Creates understeer in entry of corner.
– Makes too much suspension travel which will make it difficult to
“flick” the bike from one side to the other in a chicane.
– Will give a light feeling in the front.

First see manual. The modern
front fork of cartridge type is very sensitive for oil Level
changes, because of the small air volume Air inside the front fork
works as a spring. The different level of oil effects the spring
ratio from the middle of the stroke and has a very strong effect at
the end of the stroke.

When the oil level is raised:
The air spring in the later half stage of travel is stronger, and
thus the front forks harder.

When the oil level is lowered:
The air spring in the later half stage of travel is lessened, and
thus the front forks are softer. The oil level works most
effectively at the end of the fork travel.

Suspension
Tuning Guide-Handling How To Get It

Stock Tuning Limitations

The factories
plan on designing a bike that works moderately well for a large
section of riders and usages. To accomplish this as economically as
possible, manufacturers install valving with very small venturis.
These are then matched to a very basic shim stack which creates a
damping curve for the given suspension component. At slower speeds
this design can work moderately well, but at higher speeds, when
the suspension must react more quickly, the suspension will not
flow enough oil, and will experience hydraulic lock. With hydraulic
lock, the fork and/or shock cannot dampen correctly and handling
suffers. The solution is to re-valve the active components to gain
a proper damping curve. It does not matter what components you
have, (Ohlins, Fox, KYB, Showa), matching them to your intended use
and weight will vastly improve their action. Furthermore, if you
can achieve the damping curve that is needed, it does not matter
what brand name is on the component. Often with stock components,
when you turn the adjusters full in or out, you do not notice a
difference. In part, this is due to the fact that the manufacturer
has put the damping curve in an area outside of your ideal range.
Also, because the valves have such small venturis, the adjuster
change makes very little difference. After re-valving, the
adjusters will be brought into play, and when you make an
adjustment, you will be able to notice that it affects the way the
way the fork or shock performs.

Trying to figure out a
handling problem can be tricky. It’s hard enough dealing with the
intricacies of spring preload, rebound damping, etc., but when a
definite problem forces you to back off the throttle and take
notice, trying to determine the root cause of a handling difficulty
can be downright baffling. Is it the front or rear causing it? And
how do I know if rebound or compression damping adjustments will
help?

In this section, we’ve come up
with some of the most common handling complaints that afflict the
average rider. Some of these problems occur entering the corner,
some of them happen in mid-corner, and others can even cause
difficulty exiting a corner. Take a close look at the various
problem scenarios we’ve listed and see if one of them sounds
similar to a dilemma you’ve been struggling with. Then try our
suggested solutions to see if they make an improvement. Remember
take it one step at a time, take a test ride after each change, and
take notes on whether that change made a difference.

TANKSLAPPER

Problem: A tankslapping bike
feels unstable, especially when entering turns. The bars seem to
“twitch” excessively whenever a midcorner bump is encountered. The
bars often whip back and forth violently several times (or more)
when A tankslapping bike is accelerating aggressively over bumps
while coming out of a turn–in other words, a “tankslapper.” The
bike steers very easily, although a lack of traction is sometimes
noticeable in the rear whenever he tries to accelerate at moderate
lean angles. The bike also seems to have a dropped-down, “nose low,
rear-end-high” attitude while riding.

Cause: If the
bike feels this way, then probably there is too much front end
weight bias

Solution: The
biggest distinguishing factor in this case is the
“nose-low/rear-end-high” chassis attitude feeling. . This not only
hinders traction at the rear, but also affects the steering
geometry (steeper rake/less trail) and can cause the instability
problems. As long as the bike is suspension static sag levels set
correctly, the first step is to try less rear spring preload and/or
more front preload, to the point just before they begin to affect
handling negatively; You should remember to adjust his rebound
damping if necessary (in fact, he should check to see if decreasing
the front rebound damping in small increments helps; the forks may
be too stiff, hindering traction). If only partially successful, a
more drastic step would be changing chassis ride height; this would
involve raising the front end by dropping the fork tubes in the
triple clamps (if there’s enough material protruding above the top
clamp, to ensure front fork structural integrity), and/or dropping
the rear by shortening the rear shock (if possible).

Note: We’ve also seen a
tankslapping tendency produced by too much rearward weight bias.
The bike might try to be working the opposite of the preceding
paragraph solution, or check out the understeer/no front traction
problem scenario for more suggestions.

FLOATING RIDE

Problem: Although the bike may
have a very smooth ride while riding over potholes and such in the
city, once out in the canyons, the bike seems to “float” over the
pavement like a luxury car, with little or no pavement feedback.
When he starts to ride aggressively, the bike rocks back and forth
excessively, especially during brake/throttle transitions, and the
“floating” feeling becomes even more pronounced. Hard cornering
makes the bike feel loose, almost as if it has a hinge in the
middle. Mike’s tires might begin to chatter midcorner when
encountering bumps and accelerating over those bumps causes his
bike to wallow or weave.

Cause: The
problem here is generally not enough rebound damping.

Solution: The
ride is smooth and supple at low speeds, but higher speeds generate
greater amounts of energy that can’t be dissipated with the little
damping available. As a general rule of thumb, if either end is
pushed down firmly and quickly by hand, the suspension should
return in a smooth, controlled manner without “rebounding” once or
twice before settling down. Try stiffening up the rebound damping
in small steps, and remember to do the front and rear separately,
not simultaneously; that way he can readily see if one or the other
makes a difference. If the rebound damping is cranked up to the
maximum and the bike still feels soft and wallowy, you may need to
rebuild the suspension components.

REAR-SWAPPING

Problem: When Richard gets on
the brakes aggressively while approaching a corner, the bike’s rear
end begins to swap side-to-side, and feels as if it wants to pivot
around the front.

Cause: The
cause is too much front end weight transfer under braking. The
front end is compressing so low that the bike’s weight tries to
pivot around the steering head, causing the side-to-side
movement.

Solution: The
quickest solutions here are to increase the front fork spring
preload and/or raise the front ride height by dropping the fork
tubes in the triple clamps, or decrease the rear ride height by
shortening the shock (if possible). Try increasing the fork spring
preload first, and progressing in small increments until the
handling begins to be negatively affected (remember to watch the
rebound damping when increasing the spring preload). If that
doesn’t work, try the ride height modifications; watch for adverse
handling reactions in other areas when doing this as ride height
changes drastically affect how the bike corners. Other solutions to
try–although less effective–are to increase the compression damping
in the forks (if possible), or to decrease rebound damping in the
rear (to allow the rear tire to follow the pavement quicker).
Again, watch for adverse handling reactions in other riding
situations when test riding.

ROUGH RIDING

Problem: The bike is
uncomfortable and he feels every little bump in the road. He
doesn’t have any confidence because his bike feels nervous and
twitchy, especially over bumpy sections where it doesn’t absorb the
bumps, and his tires lose grip easily. Diving into corners during
track days, the bike is unstable and jumps around over every little
bump and crack in the tarmac.

Cause: The
rough ride is most likely due to a generally too-stiff setup–with
too much compression and rebound damping.

Solution:
First off, the rebound adjusters as outlined in the setup section,
and back the compression adjusters out to no more than the middle
of their range. This will give a starting point to work from, and
get rebound damping in the ballpark. Dialing in the rebound more
accurately can be accomplished by riding the bike over a rough
section of pavement; the suspension should not pack down (too
stiff), nor should the bike be wallowy like a Cadillac (too soft).
Riding the bike repeatedly over the same road after making small
changes to the damping adjusters is a good way to distinguish
between the characteristics and determine a good setting. Once the
rebound is set properly, the compression damping can be fine-tuned
according to the setup section. Once again, make small changes
between test sessions over the same road to feel and compare the
different settings.

BOTTOMING

Problem: When braking hard
approaching a corner, the front fork bottoms out severely,
especially over bumps. However, the fork action and overall bike
handling is fine everywhere else.

Cause: The
problem here is the ride height is set up correctly for his riding
style, but the fork action is obviously too soft whenever weight is
transferred to the front (as when hard braking).

Solution: The
from previously stiffened up the fork spring preload, and while it
helped with the bottoming problem, it unfortunately made his bike’s
chassis attitude too front-end-high, adversely affecting handling.
The cure here would be to raise the fork tubes in the triple clamps
(starting in increments of 4mm), which lowers the front end; you
could then increase fork spring preload without causing the ride
height problems mentioned previously. Care should be taken to
ensure that the front wheel/fender isn’t getting too close to
bottoming out on the lower triple clamp or radiator when lowering
the front or raising the fork tubes. If the preload adjuster
becomes maxed out during testing and dial-in, a set of heavier rate
springs or a larger preload spacer (inside the fork) may be
necessary.

HEAVY STEERING

Problem: The bike’s steering
feels super heavy at low speeds, and once he gets his bike turning
by using lots of muscle, it practically falls into
corners.

Cause: These
characteristics could be the result of a squared-off rear tire (too
much straight-line riding) or notchy or too-tight steering head
bearings;

Solution: if
the bike has a steering damper mounted, it may be adjusted too
tight. Suspension-wise, heavy steering is a typical result of
having rear ride height set too low, raking out the chassis like a
chopper.

If the same troubles occur
after trying this bike with the steering damper backed off,
checking his tire and adjusting his steering head bearings, the
problem is most likely in his bike’s chassis attitude. Front and
rear sag should be checked and set correctly, followed by another
ride to check for any changes in handling. If there is little or no
change, gradually change the geometry by either raising the fork
tubes in the triple clamps or–and has a rear ride-height
adjuster–raising the rear of his bike. When dropping the front end
of a bike by adjusting fork height, it’s a good idea to keep an eye
on clearance between the front tire and radiator, and also–on a
conventional fork–to ensure the sliders don’t bottom out on the
lower triple clamp.

UNDERSTEERING

Problem: Trouble with the
bike’s front end, especially while exiting turns, where the front
tire loses traction and pushes to the point where it’s washed out.
The steering is a bit heavy, and on uneven sections of pavement the
front tire skips over bumps and threatens to fold if pushed too
hard.

Cause: The
trouble is probably due to a combination of sag and ride height
settings that leaves his bike riding high up front.

Solution:
Having a front tire skip over bumps on the exit of a turn is a sign
that the fork is topping out–without enough sack to allow the
suspension to sink into depressions in the road.

Check the bike’s front and
rear sag settings to ensure correct spring preload. With the
preload set, take the bike for a spin to determine if there’s any
change in its behavior. If the problems persist, backing off the
front preload will drop the front of the bike a bit, quickening the
steering and letting the wheel track over bumps more effectively.
If, however, the fork starts to bottom under braking with the
preload backed off, the fork tubes can be raised in the triple
clamps to sharpen the steering while keeping the original preload
setting.

Adjustment

Setting

Effect

F o r
k

Fork Oil
Level

Oil level too
low

Forks bottom out
during hard braking or large bumps

Oil level too
high

Front wheel skips on
bumps

Compression
Damping

Too
much

Bike difficult to turn
in and will steer wide through the turn
Front wheel skips on bumps
Forks judder when braking in a straight
Front end feels harsh on small bumps

Not
enough

Forks dive too
quickly, possibly bottoming out
Rear end wants to come around during hard braking
Front end has a mushy and semi-vague feeling, similar to lack of
rebound damping

Rebound
Damping

Too
much

Front end chatters
coming out of corners
Forks pack down on fast bumpy pavement
Front end wiggles or tank-slaps on hard acceleration out of bumpy
corners
Harsh ride due to forks packing down

Not
enough

Excessive pogo action
through chicanes
Front end shakes (not chatters) in corners
Front end shoots up too fast after braking
Feels plush when riding straight, but mushy in corners and traction
feel is poor
When flicking into a corner at speed, the bike will porpoise or
wallow a bit before settling down

Ride
Height

Too
low

Lack of high speed
stability
Easy turn-in into corners

Too
high

Sluggish or high
effort turn-in into corners

Spring
Rate

Too
soft

Forks compress too
much on smooth turns
Forks bottom out during hard braking or large bumps
Creates oversteer
Can cause front to tuck under
Turns easily into corners

Too
stiff

Creates understeer
Lose front end on corner entry
Harsh in corners
Front end chatters coming out of corners
Bike difficult to turn in
Feels good under braking
Front wheel skips on bumps

Rear
Shock

Compression
Damping

Too
much

Shock rigid and harsh,
but not as bad as too much rebound damping
Rear wheel skips when braking on rippled pavement
Very little rear end squat on acceleration

Too much kicking up
when braking hard
Bike wallows when exiting corners or in long rolling dips in
sweepers
Rear wheel chatters under hard acceleration over bumps
Too much chassis pitch/pogo stick action

Ride is soft
Rear end squats on acceleration
“Light” feeling on the front

Too
stiff

Easy turn-in to
corners
Ride is harsh
Poor rear wheel traction

DEFINITIONS

Every activity has its own
language. Learning a new skill sometimes feels as if it requires
scaling a linguistic learning curve that makes surmounting Mt.
Everest seem like a day hike. To the uninitiated–not that any Sport
Rider reader could be accused of this–the language of motorcyclists
can seem just as daunting. So, to make sure we’re all standing on
top of the same hill, peruse the terminology below to help speed
yourself along to suspension enlightenment.

Bottoming
(also called bottoming out)–when a suspension component reaches the
end of its travel under compression. Bottoming is the opposite of
topping out. Cartridge Fork–a sophisticated type of fork that
forces oil through bending shims mounted to the face of damping
pistons contained within the fork body. The primary advantage of
cartridge forks is they are less progressive than damping rod
forks. The shims allow damping control at very low suspension
speeds while high speeds deflect the shims more–causing less
high-speed damping than fixed orifice damping rods. The resulting
ride is firmer with less dive under braking while simultaneously
lessening the amount of force square-edged bumps transfer to the
chassis.

Damping
General is viscous friction. It is caused when liquids are
forced through some type of restriction. The key thing to remember
about damping is that it is dependent on fluid movement. This means
a shock creates no damping force unless there’s movement-movement
of the damper unit in compression or rebound as opposed to bike
movement. Damping cares about vertical wheel velocity, not bike
speed.

Compression
Damping–controls the initial “bump stroke” of the
suspension. As the wheel is forced upward by the bump, the
compression circuit controls the speed at which the suspension
compresses, helping to keep the spring from allowing an excessive
amount of travel or bottoming of the suspension. Damping–viscous
friction caused by forcing a fluid through some type of
restriction. Damping force is determined by the speed of the fluid
movement, not the distance of suspension travel. This is
DAMPENING

Damping Rod
Fork–a simple type of fork that utilizes a tube with holes
in it to create compression and rebound damping, delivering an
extremely progressive damping curve. The faster the wheel moves
vertically, the more oil that is shoved through the holes.
Typically, damping rod forks have very little low-speed damping and
a great deal of high-speed damping. The ride is characterized by
excessive fork dive under braking and hydraulic lock when
encountering square-edged bumps. Any change to the damping rod
system, such as changing the size of the holes or altering the oil
viscosity, affects the entire speed range.

High-Speed
Damping–damping to control fast vertical movements of
suspension components caused by road characteristics such as
square-edged bumps. High-Speed damping is independent of motorcycle
speed.

Low-Speed
Damping–damping to control slow vertical suspension
movements such as those caused by ripples in pavement. (This is
also independent of motorcycle speed.)

Rebound
Damping–controls the extension of the fork or shock after
it compresses over a bump–hence the term “rebound.”

Fork Oil
Level–the level of oil within the fork as measured when
fully compressed without the spring installed. It is used in tuning
the amount of air contained inside the fork. Since compressing air
makes it act as a spring, raising the oil level leaves less room
for air, resulting in a rising rate throughout the fork’s travel.
Reducing the oil level reduces the force at the bottom, giving a
more linear rate.

Free Sag–the
amount the bike settles under its own weight. Both streetbikes and
race bikes require 0 to 5mm of free sag on the rear. The bike
should not top out hard.

Packing–a
phenomenon caused by excessive rebound damping. When a series of
bumps, such as ripples, are encountered the suspension does not
rebound completely between bumps and compresses (packs) further
down on each successive bump. This can drastically change steering
geometry if packing occurs on only one end of the
motorcycle.

Preload–the
distance a spring is compressed from its free length as it’s
installed with the suspension fully extended. Preload Adjuster–a
method of adjusting suspension components’ preload externally.
These can be ramped or threaded.

Rake–the
steering neck angle (not the fork angle) relative to vertical,
which varies with changes in ride height. For example, the rake
angle decreases when the front end compresses or is lowered.
Changes in tire diameter can also influence rake by altering the
ride height.

Ride
Height–suspension adjustments (raising or lowering the
fork or lengthening or shortening the shock) to alter the chassis
attitude of the motorcycle.

Shock preload can be altered
with a spanner wrench or with the time honored hammer and
punch.

Sag–the
amount the front or rear of the bike compresses between fully
topped out and fully loaded with a rider (and all of his riding
gear) on board in the riding position. Sag can also affect steering
geometry. Extra sag on the front end will decrease the effective
steering head angle, quickening steering, while too little front
sag will slow steering. However, too much front sag combined with
too little rear sag could make the bike unstable. How to set your
sag

Spring–a
mechanical device, usually in the form of a coil, that stores
energy. When compressed, more energy is stored. Springs are
position sensitive, caring only how much they have been compressed,
not how quickly (as with damping).

Suspension
Fluid–used inside a shock absorber to create damping when
forced through orifices or valving. The fluid is also used for
lubrication and should be incompressible.

Topping
Out–occurs when the suspension extends to its limit. A
shock with a spring of the proper rate mounted should have just
enough force to top out without a rider on board.

Trail–the
horizontal distance between the front end’s point of rotation (i.e.
where a line drawn through the steering head would intersect the
ground) and the contact patch of the tire. Since trail is dependent
on rake, it is a variable dimension that changes proportionally
with the variation of rake during suspension action. For example,
trail drops off dramatically when the bike reaches full dive under
braking, giving a rider more leverage to initiate steering
inputs.

Triple Clamp
Offset–the distance from the center of the fork tubes to
the steering stem center. The greater the offset, the smaller the
trail dimension.

Unsprung
Weight–the weight of every part of the motorcycle that is
between the road and suspension (i.e. wheels, brakes, suspension
components below the springs, etc.).